1. Field of the Invention
This invention relates to an article of manufacture exhibiting cyclic oxidation-hot corrosion resistant properties comprising a non-eutectic nickel-base superalloy having a microstructure substantially free of carbides in the form of aligned fibers consisting essentially of, on a weight basis, 1-9% Re, 0-2% Ti, at least 2% Al, 3-12% Cr, 1-5.9% Ta, 0-0.5% C, 2-12% Co, 2-10% W, less than 1% V, 2-10% Mo, 0-5% Cb, 0-3% Hf, 0-1.5% Zr and 0-0.20% B, the balance being essentially Ni and incidental impurities.
2. Description of the Prior Art
Quigg et al. U.S. Pat. No. 3,526,499 issued Sept. 1, 1970 (filed Aug. 22, 1967) broadly describes nickel-base alloys containing substantial amounts of solid solution strengtheners. Quigg teaches the balanced use of tantalum, tungsten, and molybdenum in order to achieve strength properties without depreciating the oxidation resistance properties of Quigg's alloys. Quigg, however, failed to recognize the exceptional cyclic oxidation-hot corrosion resistant properties associated with nickel-base alloys containing on a weight percent basis, less than 6.0% w/o tantalum and at least 1.0% w/o rhenium, especially nickel-base alloys containing at least 4.0% w/o molybdenum.
Smashey's U.S. Pat. No. 3,904,402, issued Sept. 9, 1975 (filed June 1, 1973) broadly describes eutectic nickel-base alloys containing rhenium and a carbide reinforcing fiber phase exhibiting improved high temperature strength stress rupture properties. Smashey teaches the use of 4-7% w/o vanadium for enhancement of carbide fiber as well as matrix strengthening. Smashey teaches the limited use of molybdenum, i.e. up to about 3% w/o, however preferably omits the use of Mo. Smashey also preferably limits tungsten to about 2-4% w/o in nickel-base superalloys. Smashey summarily teaches the additive use of vanadium and the restrictive use of molybdenum and tungsten. Recent evaluations of Smashey's eutectic alloys has illuminated their generally limiting brittle (non-ductile) transverse strength characteristics.
More recently, interdependent relationships of various alloying elements, e.g. vanadium, molybdenum and tungsten, relative to transverse ductility, cyclic oxidation resistant and hot corrosion resistant eutectic nickel-base alloys containing rhenium and a carbide reinforcing fiber phase have been recognized and are described in M. F. Henry's eutectic nickel-base superalloy invention U.S. Ser. No. 34,154, now U.S. Pat. No. 4,284,430.
Although Henry's Ser. No. 34,154 eutectic nickel-base Re containing carbide fiber reinforced superalloys have improved properties over Smashey's alloys, heretofore non-eutectic nickel-base Re containing superalloys exhibiting significant and substantial cyclic oxidation as well as hot corrosion resistant properties have remained undefined.